The present invention relates in general to battery housing structures, and deals more particularly with battery packs used by portable electronic devices. Specifically, the invention deals with a battery pack for packaging within a cellular telephone device.
The growth in the use of portable electronic devices such as, for example cellular telephones, personal digital assistants commonly known as PDA""s, portable music players, and the like, has driven the design of such devices to become smaller and more convenient. Consumers have become accustomed to the convenience and portability of such electronic devices, particularly, cellular telephones and have demanded that those cellular telephones become even more convenient and even more portable. The constant thrust in cellular telephone design is to make them as small as possible. To accomplish this, the cellular telephone housing and the housing of the battery pack powering the cellular telephone have been designed to meet stringent size restrictions and to be as light as possible. Typical battery housings for cellular telephones incorporate a plastic case or enclosure for holding the battery cells and often other electrical circuitry components necessary to build-up the complete battery structure to power the phone when the battery housing is engaged with the cellular telephone.
A battery housing or enclosure such as described above is typically preformed and expands all dimensions of width, length and height of the battery package compared to the battery cell contained within and carried by the housing. The size of the battery package is further enlarged to accommodate other component parts such as mechanical engaging means to attach the battery package into the cellular telephone, electronic circuitry for charging control and battery cell protection, interface contact area to make electrical contact from the battery package to the cellular telephone. One example of such a complete prior art preformed battery package in a case is shown, for example, in U.S. Design Patent Des. 423,449 assigned to the same assignee as the present invention.
In an attempt to minimize the size and weight of battery housings for portable electronic devices, particularly cellular telephones, lightweight plastic materials that have electrical insulative properties have been used to fabricate battery housings with relatively thin walls. The resultant battery housing often exhibits low structural integrity and tends to be relatively easy to break and fracture upon dropping and is generally unsatisfactory for use in cellular telephones and portable electronic devices. Additionally, the smaller sized battery package often results in a reduction of the relative electrical power density capacity available as the battery cells are likewise reduced in physical size to fit into the smaller sized battery pack. Therefore, a need exists for a battery package to power cellular telephones and portable electronic equipment that exhibits the electrical insulative properties of a plastic battery housing while providing a solution to achieve even smaller size battery packs without sacrificing the available relative electrical power density capacity of the battery pack.
Accordingly, it is an object of the present invention to provide a battery pack for use with portable electronic devices, particularly, cellular telephones.
It is another object of the invention to provide a battery package structure that is suitable for a smaller physical design.
It is yet another object of the invention to maximize the available relative electrical power density capacity in such a battery package.
It is another object of the present invention to provide a battery package without a preformed enclosure for a cellular telephone.
It is yet a further object of the present invention to provide a battery package that is encased by a low temperature melting resin.
It is a still further object of the invention to provide a battery package that is encased with a resin capable of being injection molded with relatively low pressure.
It is a still further object of the present invention to provide a battery package that is easy to manufacture.
In accordance with one aspect of the present invention, a battery pack is provided for an electronic device. The battery pack includes at least one battery cell assembly. An interface assembly cap has a size and shape for complementary engagement with one end portion of the battery cell assembly. The interface assembly cap provides an electrical connection means between the cell and the electronic device. The interface assembly further provides an electrical connection to the cell whether the battery pack is positioned within or outside the electronic device. A low-temperature melting resin encases the battery cell assembly.
Preferably, the battery pack includes an end cap having a size and shape for complementary engagement with an end portion of the battery cell opposite the interface assembly end portion.
Preferably, a low-temperature melting resin further encases the end cap and the interface assembly cap.
Preferably, the interface assembly cap includes an externally accessible positive, negative and ground voltage reference potential contact.
Preferably, the voltage reference potential contacts are positionally located in accordance with the positional locations of the voltage reference potential contacts of the electronic device with which the battery pack is used.
Preferably, the battery pack includes means for aligning the battery pack when positioned within the electronic device.
Preferably, the cell further comprises a flat cell.
Preferably, the battery pack is for use in a cellular telephone.
Preferably, the cell has at least one member extending lengthwise of the cell for increasing the stiffness and lengthwise rigidity of the battery cell assembly.
In another aspect of the battery pack of the present invention, a thin foil tape is wrapped around the battery cell assembly.
In a second aspect of the invention, a method for molding a battery pack for an electronic device is presented. The method comprises the steps of providing at least one battery cell assembly having a desired shape and size and a positive voltage potential terminal and a negative voltage potential terminal; providing an electrical connection means for interfacing between the battery cell assembly and the electronic device; electrically connecting the electrical connection means to the battery cell assembly wherein the positive voltage potential terminal is connected to the positive voltage supply path of the electrical connection means and the negative voltage potential terminal is connected to the negative voltage supply path of the electrical connection means; placing the electrical connection means and the battery cell assembly into a mold; positioning and maintaining the electrical connection means adjacent to and in contact with one end of the battery cell assembly; closing the mold; pouring a low temperature melting resin into the mold to encase the electrical connection means and battery cell assembly; and removing the thus molded battery pack from the mold.
Preferably, the method step of providing an electrical connection means includes providing a printed circuit board.
Preferably, the method step of providing an electrical connection means includes providing a gold plated nickel conductor.
Preferably, the step of placing the electrical connection means into a mold includes the step of placing the electrical connection means into a metal mold.
Preferably, the method step of pouring includes pouring a polyamide.
Preferably, the method step of pouring includes pouring a polyurethane.
Preferably, the method includes the step of molding under low pressure.
Preferably, the method includes the step of providing a flat battery cell assembly.
In a third aspect of the invention, a battery pack for a cellular telephone is presented. The battery pack includes at least one battery cell assembly having a desired shape and size and a positive voltage potential terminal and a negative voltage potential terminal.
An electrical conductive path is provided to interface the battery cell assembly and the cellular telephone, wherein the electrical conductive path has a positive voltage potential contact electrically connected to the battery cell assembly positive voltage potential terminal and a negative voltage potential contact electrically connected to the battery cell assembly negative voltage potential terminal. The positive and negative voltage potential contacts are located and positioned for contact with the positive and negative voltage potential terminals of a cellular telephone with which the battery pack is used.
Preferably, a low temperature melting resin encases the battery cell assembly and the electrical conductive path to form a relatively thin wall molded battery pack.
Preferably, the low temperature melting resin is polyamide.
Preferably, the low temperature melting resin is polyurethane.
Preferably, the electrical conductive path interfaces with charging control circuitry in the cellular phone.
Preferably, the electrical conductive path interfaces between the battery cell and battery cell monitoring and status indication circuitry in the cellular phone.
Preferably, the electrical conductive path is a printed circuit board.
Preferably, the interfacing printed circuit board further includes charging control circuitry.
Preferably, the interfacing printed circuit board further includes battery cell voltage and current monitoring and status indication circuitry.